"If the sinking of the _Sussex_ had been an isolated case," says the Note, "that would enable the Government of the United States to hope that the officer responsible for the deed arbitrarily exceeded his instructions, or in criminal negligence failed to observe the prescribed measures of precaution, and that satisfaction might be done to justice by his appropriate punishment, associated with a formal disavowal of his conduct and the payment of appropriate compensation by the Imperial Government. But although the attack on the _Sussex_ was evidently indefensible and caused so tragic a loss of human life that it appears as one of the most terrible examples of the inhumanity of the submarine warfare as waged by the commanders of German vessels, it unhappily stands not alone." After recalling former protests by the American Government and Germany's unlawful attempt to close a part of the high seas, the Note continues:-- "The international law, which here applies and upon which the United States Government based its protest, is not of recent origin or based on purely arbitrary principles established by agreement. On the contrary, it rests on obvious principles of humanity, and has long been in force, with the approval and the express assent of all civilised nations. The Imperial Government insisted, notwithstanding, on prosecuting the policy announced, while it expressed the hope that the existing dangers, at least for neutral ships, would be restricted to a minimum by instructions given to the commanders of its submarines, and assured the United States Government that it would apply every possible precaution to respect the rights of neutrals and protect the lives of non-combatants. "In pursuit of this policy of submarine warfare against its enemy's trade, so announced and begun despite the solemn protest of the United States Government, the Imperial Government's submarine commanders have practised a procedure of such reckless destruction as made it more and more clear during recent months that the Imperial Government has found no way to impose upon them such restrictions as it had hoped and promised. The Imperial Government has repeatedly and solemnly assured the United States Government that passenger ships, at least, would not be thus treated, and yet it has repeatedly allowed its submarine commanders to disregard these assurances with impunity. Even in February of this year it announced that it regarded armed merchantmen in enemy possession as part of the armed naval forces of its adversaries, and would treat them as warships, while it bound itself, at least implicitly, to warn unarmed vessels and guarantee the lives of their passengers and crews; but their submarine commanders have freely disregarded even this restriction.